1. Field of the invention
The present invention relates to protective clothing for use in a toxic environment and, more particularly, to an improved passthrough coupling design for supplying air and/or liquid to the suit in a chemical warfare agent environment.
2. Description of the Background
Chemical protective suits are used by emergency personnel to protect them against an array of toxic chemicals. These chemicals include blistering agents such as lewisite or mustard gas, choking agents such as phosgene (or CG as designated by the military), blood agents including cyanide based compounds such as hydrogen cyanide (AC), and nerve agents such as sarin, tabun, soman, and others.
The nerve agents are the most useful to terrorists because of the small quantity needed to inflict a substantial amount of damage. VX and sarin are the most toxic of the nerve agents and these can be synthesized by any competent chemist using limited laboratory facilities. For example, on Mar. 20, 1995, there was a terrorist sarin gas attack on the Tokyo subway that killed nearly a dozen people and injured approximately 5000 others. The incident involved six devices all set to go off on five different subway cars. A variety of protective suits have been developed to protect wearers against the adverse effects of these chemicals as well as biological, nuclear and other environmental contaminants or conditions. The design aspects of these highly specialized suits depend largely upon their specific applications. However, if just trace amounts of these toxic vapors penetrate the chemical protective suit the result can be severe injury or death. Consequently, most all of such suits employ an external pressurized air source for introducing pressurized clean filtered breathable air into the garment.
For example, U.S. Pat. No. 5,127,896 to de Gaston discloses an integrated anthromorphic suit with a breathing regulator for protecting the user of the suit from hostile environments. It also discloses an air hose 38 for delivering pressurized air to the user.
U.S. Pat. No. 4,558,466 to Kristensson discloses a vest for use in polluted atmosphere and a means for delivering fresh air to the user and knobs to control the temperature and heat of the delivered air.
U.S. Pat. No. 4,458,680 to Childers, et al discloses a protective supplied breathing air garment. An air supply line 23 provides a flow of breathing air to the user. Air supply line 23 is provided with a threaded female collar 25 for attaching to a retaining nipple 24 externally provided on the suit to provide an air-tight seal between the suit and the air supply line.
U.S. Pat. No. 3,777,750 to Savornin discloses a protective garment for conducting work in a deleterious atmosphere.
U.S. Pat. No. 3,457,918 to Dibelius et al. discloses a protective suit coupled with an air supply source for maintaining a viable atmoshpere inside the suit.
U.S. Pat. No. 3,394,260 to Phipps discloses a protective suit with a means of supplying fresh air to the protective suit 10 using a blower 38 through a tube 40.
U.S. Pat. No. 3,345,641 to Jennings discloses a ventilated space suit. The space suit 10 is provided with a portable life support system 20 which comprises an oxygen reservoir 22 connected to one end of supply line 28. The other end of supply line 28 is to the space suit 10 which also has an exhaust line 30 for removing the waste CO.sub.2.
U.S. Pat. No. 3,292,179 to Iacono discloses a protective garment with a mechanism for circulating air. Air is introduced into the garment 10 through inlet ports 30 which communicate with the inner passageway 25. The exhaust air exits from the port 31 through the outer air passageway 26.
U.S. Pat. No. 4,458,680 to Edward L. Childers et al. shows one exemplary closed circuit system in which air is recirculated.
In some cases, chemical warfare suits may also employ liquid cooling systems that circulate liquid coolant from an external source. Whether air, water, or other fluid, the fluid must be pumped into the suit or expelled therefrom through tubes which are connected at suit couplings, i.e., "passthrough" assemblies. These passthrough assemblies must safeguard the integrity of the suit, especially in the chemical warfare context which often requires a hermetic seal. In such cases the couplings must be of the highest integrity and provide maximum protection against contamination. The designer must be cognizant of the fact that many chemical warfare agents are specifically intended for maximum penetration at seams and couplings.
There have been previous efforts to improve the integrity of air and liquid couplings or "passthroughs".
For instance, U.S. Pat. No. 5,516,122 to Caffee discloses a ultra-high vacuum elastomer O-ring seal. The surface of the O-ring seal conforms to the contours of the mating grooves on the surface of the metal flanges as the flange joint is tightened. This causes an increase in the area of contact between the O-ring and the mating surfaces and thus provides for an efficient sealing mechanism. Additionally, U.S. Pat. No. 5,118,141 to Miyashita discloses a union joint for hermetically connecting pipes; U.S. Pat. No. 4,671,546 to Arav discloses a device for sealing a bolt hole in a fluid containing assembly; U.S. Pat. No. 4,252,332 to Nakayama et al. discloses a sealing device for use in a swash-plate type compressor; U.S. Pat. No. 4,090,029 to Lundeberg discloses a conductive O-ring 18 that provides a tight seal and metal-to-metal contact; U.S. Pat. No. 3,831,954 to Longfellow discloses an improved gasket joint connection; and U.S. Pat. No. 3,746,348 to Stone discloses an O-ring with cylindrical nubs along its circumference to facilitate efficient sealing of flange type fittings.
While these and other couplings may have value in specific applications, they are unable to provide maximum protection against contamination in a chemical warfare environment. Certain chemical warfare agents such as Sarin (GB, a nerve agent) are capable of penetrating into the suit through the couplings. Thus, it would be a great advantage to provide an improved design for both air and liquid passthrough couplings to ensure maximum protection against contamination, especially in a chemical warfare environment where penetrating chemical warfare agents such as Sarin may be present.